Long term capital gain calculation on under-construction land

My Scenario is:

• We have land purchased in 2012 in an under-construction township for 22 L.
• Paid installments as per the asks from builder till 2014. Till 2014 about 15L was in totality paid. 
• Although, further requests for installments didn't come because builder couldn't simply do land acquisition.
• After waiting for many years, I had sold it in 2022 for exactly same amount to someone local there. Basically,  land acquisition never happened till that time.

My questions are: 

• This is a case of long term capital gain?
• If Yes, how do we calculate long term capital gain for this property? Only allotment happened in 2012 but Possession / Registration never happened on it.